Fix Schedule UI regressions and complete non-RU/EN locale translations

- Duration now sums segments + transfers (last arrival − first departure)
  for multi-leg/connecting in Schedule, matching TZ §4.1.14.3 and Angular.
- Default day auto-expands per TZ §4.1.14: current-week today, future-week
  first valid day, last-valid-day fallback when earlier days are out of
  window.
- Aircraft model no longer leaks into collapsed rows; shown only when
  expanded AND direct, mirroring Angular's
  operator-logo-and-model [showModel]="expanded && direct".
- Week tabs use MONTH-SHORT.* translation table so Russian renders
  "27 апр. - 3 май." instead of genitive "мая" from Intl.
- "Ранее искали" → "Вы искали" across all 9 locales (TZ §4.1.9.5).
- Sort-arrow headers compacted (inline-flex nowrap, zero gap) so labels
  stay on one line next to the chevrons.
- robots.txt allows Yandex/Googlebot/* with no Disallow (TZ §4.1.20).
- 6 non-RU/EN locales (de/es/fr/it/ja/ko) + zh were missing ~45 strings
  each; translated from Angular where present, hand-translated otherwise
  so every locale is down to the two intentional `.undefined` stubs.

config/public/robots.txt

@@ -0,0 +1,8 @@
+User-agent: Yandex
+Allow: /
+
+User-agent: Googlebot
+Allow: /
+
+User-agent: *
+Allow: /